Project Summary/Abstract Drop-out rates from medical clinics in the first months following linkage to HIV care are as high as 50%, with 31-46% of patients dropping out after the first visit. People Living with HIV (PLWH) who are not consistently retained in care are at risk for: delayed antiretroviral treatment (ART) initiation, reduced ART adherence, unsuppressed viremia, and mortality. Moreover, poor retention means effective ART cannot be leveraged to prevent further HIV transmission. The long-term goal is to improve the HIV care cascade by developing behaviorally-based interventions with broad applicability that can be executed with minimal cost and effort in community-based HIV care medical settings. The objective of this proposal, which is the next step in attaining the long-term goal and building on our successful R34 study, is to conduct a fully powered, randomized controlled trial (RCT) to assess the efficacy of a brief, 2-session acceptance-based behavioral therapy (ABBT) intervention to enhance retention in HIV care. The central hypothesis is that participants' informed disclosure of HIV status to members of their support system, facilitated through increased acceptance of HIV status early in medical care, will increase their longitudinal commitment to care. The aims of this proposal are: (1) To test, in a 2-arm RCT, the efficacy of the ABBT intervention on retention in care and virologic suppression (primary outcomes); and, ART adherence, disclosure of HIV status, perceived social support, HIV stigmatization (secondary outcomes), relative to an Enhanced-Treatment-as- Usual condition; and, (2) To examine the degree to which retention in HIV care and virologic suppression are mediated by (a) increased HIV acceptance (and decreased HIV experiential avoidance) and (b) increased willingness to disclose HIV status. The sample will consist of 270 HIV patients who are new to care, recruited from two large, geographically and ethnically diverse HIV medical care settings in Providence, R.I., and New Orleans, L.A. The approach is innovative in that it departs from the status quo by using brief acceptance-based psychotherapy techniques, delivered in-person and by telephone, to increase acceptance of HIV status and promoting careful and thoughtful serostatus disclosure as a specific mechanism to support retention and virologic suppression. Upon successful completion of the proposed R01 research, this study will contribute significant actionable data clarifying the impact and mediational mechanisms of ABBT on medical care retention and virologic suppression. Thus, it will lay the groundwork for the dissemination of a simple, low-cost intervention that can be integrated into usual HIV care.